Interference in the radiation of two point-like charges

Energy-momentum and angular momentum carried by electromagnetic field of two point-like charged particles arbitrarily moving in flat spacetime are presented. Apart from usual contributions to the Noether quantities produced separately by particles 1 and 2, the conservation laws contain also joint contribution due to the fields of both particles. The mixed part of Maxwell energy-momentum density is decomposed into bound and radiative components which are separately conserved off the world lines of particles. The former describes the deformation of electromagnetic clouds of ``bare'' charges due to mutual interaction while the latter defines the radiation which escapes to infinity. The bound terms contribute to particles' individual 4-momenta while the radiative ones exert the radiation reaction. Analysis of energy-momentum and angular momentum balance equations results the Lorentz-Dirac equation as an equation of motion for a pointed charge under the influence of its own electromagnetic field as well as field produced by another charge.Comment: 46 pages, 8 figure

COVID-19. Who can help us?

COVID-19 coronavirus infection, despite its high contagiousness and rapid spread, is not accompanied by the development of the disease in most infected people. The main cause of clinical manifestations of this infection is inflammation of the lung tissue, which affects the same parts of the organ as bacterial forms of pneumonia, accompanied by identical functional disorders. Functional disorders are caused by inflammatory transformation of tissues, not by the pathogen itself, and are manifested not so much in lung ventilation as in the effect through the pulmonary vessels on the blood circulation of the entire body. Most patients actually cope with the disease on their own, as there are no effective treatment methods yet. However, when the disease has a rapid and progressive course, pathogenetic methods are needed to really help patients, which can help the body adapt and avoid critical situations

Photon decay gamma->nu anti-nu in an external magnetic field

The process of the photon decay into the neutrino - antineutrino pair in a magnetic field is investigated. The amplitude and the probability are analysed in the limits of relatively small and strong fields. The probability is suppressed by a factor (G_F m^2_e)^2 as compared with the probability of the pure electromagnetic process gamma -> e- e+. However, the process with neutrinos could play a role of an additional channel of stellar energy-loss.Comment: 8 pages, LaTeX, typos fixed, minor modifications, version accepted to Physics Letters

Hygienic requirements of urban living environment in the Russian Federation and in Italy: a comparison

Introduzione/scopo. La pianificazione urbana tende a contenere e regolamentare la crescita urbana consentendo uno sviluppo sostenibile a livello ambientale, sociale e sanitario. Nel presente lavoro gli autori hanno confrontato i quadri normativi della Federazione Russ e dell’Italia ponendo particolare attenzione agli aspetti urbani degli spazi abitativi. Metodo. Considerando la ponderosa produzione normativa nei due paesi, il lavoro ha preso in esame le normative a livello nazionale per l’Italia e federale per la Russia, tenendo principalmente conto dei seguenti aspetti: strumenti di pianificazione urbana e protezione ambientale e sanitaria degli spazi abitativi. Risultati. I problemi relativi alla sicurezza igienico-sanitaria dell’ambiente di vita in Russia sono essenzialmente riconducibili a due sistemi normativi (SNiP e SanPiN), mentre in Italia rientrano nel D.M. 05/07/1975. I principi fondamentali della pianificazione urbana in Russia sono dettati da una norma federale, mentre in Italia sono recepiti nel Piano Regolatore Generale (PRG) comunale e nei diversi regolamenti locali, dove si riasriassume tutta la normativa sovraordinata. Gli aspetti legati alla qualità ambientale, infine, in entrambi i paesi sono disciplinati da varie leggi specifiche (federali e statali); un articolato sistema di norme che tengono conto dei potenziali impatti sulla salute e sull’ambiente Conclusioni. Gli autori ritengono che dovrebbero essere sviluppati, specialmente in Italia che si trova nettamente più indietro da questo punto di vista, strumenti normativi chiari e aggiornati aventi per oggetto l’igiene degli edifici e degli ambienti urbani, basati sulle più recenti acquisizioni di letteratura scientifica internazionale nell’intento di garantire i più alti standard in materia di tutela della Salute Pubblica.Aim. Urban planning tries to contain and regulate the uncontrolled growth of cities, encouraging their sustainable development at environmental, social and health levels. In the present work, the authors compare the regulatory frameworks of the Russian Federation and of Italy, with particular attention paid to the urban aspects of living spaces. Method. Considering the extant normative production in the two countries, the authors examine national legislation for Italy and federal legislation for Russia, mainly taking into account the following aspects: urban planning tools and environmental and sanitary protection of living spaces. Results. Hygienic-sanitary requirements regarding living environment in Russia are essentially expressed by two regulatory systems (SNiP and SanPiN), while in Italy they are regulated by the D.M. 07/05/1975. The main principles of urban planning in Russia are expressed by federal standards, while in Italy they are incorporated in the Municipal General Plan (PRG) and in the various local regulations, where all the superordinate regulations are summarized. Finally, aspects related to environmental quality in both countries are governed by various specific laws (federal and state); a complex system of rules that take into account potential impacts on health and the environment. Conclusions. The authors reckon that clear and updated regulatory tools should be developed, especially in Italy that lags behind, regarding the building and urban hygiene, relying on the most recent acquisitions of international scientific literature in order to guarantee the highest standards in Public Health safeguard

Interference of outgoing electromagnetic waves generated by two point-like sources

An energy-momentum carried by electromagnetic field produced by two point-like charged particles is calculated. Integration region considered in the evaluation of the bound and emitted quantities produced by all points of world lines up to the end points at which particles' trajectories puncture an observation hyperplane $y^0=t$. Radiative part of the energy-momentum contains, apart from usual integrals of Larmor terms, also the sum of work done by Lorentz forces of point-like charges acting on one another. Therefore, the combination of wave motions (retarded Li\'enard-Wiechert solutions) leads to the interaction between the sources.Comment: 38 pages, 13 figures, LaTeX2

Crude Oil Logistics, Production and Refining in Northern Europe

To develop the programs to supply crude oil to North European refineries, it is necessary to take into account refineries' location, oil refining capabilities and transportation infrastructure capacity. The paper envisages the geographic allocation of refineries and contains the evaluation of refineries' capacities. Sustainable operations of the refineries are determined by transportation system. The assessment of capacity of crude oil transportation to the refineries is conducted. Change in the refineries' capacities and the utilization of the refineries' in the Northern European region was studied. Research is performed for the period of 2005/2015. The study yielded the trend towards increase in crude oil output and refining in the region. If this trend persists, the cargo flow of imported crude oil and the utilization of logistics infrastructure may increase. According to the study, the existing transport and refining infrastructure in the region is able to handle the increasing imported crude oil flow. Keywords: Oil Logistics, Oil Production, Oil Refining. JEL Classifications: F23, L71, L95, O52, R1

In the Footsteps of the Problem of the Third Century BC

Introduction. The problem of selecting monuments of the 3rd century BC in the Early Sarmatian culture came into sight during the process of discussing the reasons for the fall of Scythia, when it became clear that the Early Sarmatian funerary monuments in the Northern Black Sea steppes are recorded starting from the 2nd century BC, a hundred years after the alleged destruction. Methods and materials. During the research process the scientists came to the conclusion that there are no imports of the 3rd century BC in the burials of the Lower Volga region and the Southern Urals. Some researchers stated the absence of monuments of this time in the indicated territories, while others continued to search for new approaches. As a result, they proposed the the method of “clamped” dating, which allows us to distinguish a stratum between well-dated complexes of the 4th and 2nd – 1st centuries BC. Analysis. In the course of clarifying the situation in the original Sarmatian territories, some researchers have decided to devide the reference early Sarmatian burial ground Prokhorovka into two groups, not only chronologically, but also culturally. The 3rd century BC became a time separating these groups, elusive according to these authors, not only in the Northern Black Sea region, but also in the Volga-Ural steppes. Opposing this point of view, supporters of the culture of continuous development in the 4th – 1st centuries BC pay attention to the unity of the funeral rite throughout the entire period, and the lack of well-dated imports is explained by crisis phenomena and migration processes, when old contacts with civilizations are crashing and new ones have not yet been established. The discussion that unfolded in the 90s of the 20th century with the accumulation of new materials and clarification of old dates periodically revived, updated with new participants, but the position of opponents has not really changed. The proposed article is devoted to evaluating the arguments of both sides. Results. The method of “clamped” dating is not the most universal, considering the constantly growing database of sources and its corrections. But this method works and many scientists continue to rely on it. A simple statement of the impossibility of identifying monuments of the 3rd century BC, when the existence of the monuments of this time is asserted, seems even more surprising than the assertion of the “hiatus” of the 3rd century BC, in the Volga-Ural steppes region

Pair creation by a photon in an electric field

The process of pair creation by a photon in a constant and homogeneous electric field is investigated basing on the polarization operator in the field. The total probability of the process is found in a relatively simple form. At high energy the quasiclassical approximation is valid. The corrections to the standard quasiclassical approximation (SQA) are calculated. In the region relatively low photon energies, where SQA is unapplicable, the new approximation is used. It is shown that in this energy interval the probability of pair creation by a photon in electric field exceeds essentially the corresponding probability in a magnetic field. This approach is valid at the photon energy much larger than "vacuum" energy in electric field: $\omega\gg eE/m$. For smaller photon energies the low energy approximation is developed. At $\omega\ll eE/m$ the found probability describes the absorption of soft photon by the particles created by an electric field.Comment: 15 pages, 6 figure

Accurate FTIR determination of boron concentration in CVD homoepitaxial diamond layers

The intensive development of technology for fabrication semiconducting CVD diamond layers poses an important task of developing a precise and non-destructive method for estimation the boron content in thin epitaxial layers. For bulk and uniformly doped diamond samples, the infrared optical spectroscopy successfully performs such a role. Here we propose a correct method to determine the boron concentration in CVD homoepitaxial diamond layers from FTIR spectra. The method is the natural advancement of the existing technique for bulk samples. The feature of the novel technique is the accurate accounting of passing radiation through a multilayered structure with different thicknesses of absorbing media for special absorbing mechanisms. For this situation, an expression for the effective optical density is obtained. We have demonstrated the benefit of the method for a set of samples with CVD homoepitaxial layers grown on various HPHT substrates with and without nitrogen impurity. The measured FTIR spectra were subdivided into relevant sections responsible for the specific absorption mechanisms, and the correct amplitudes of the boron absorption peaks were derived. The data obtained from FTIR spectra is thoroughly compared to the charge carrier concentration derived from electrical capacitance-voltage measurements.Comment: 18 pages, 7 figures, 1 tabl